With the increasing recording density of disk drives in recent years, the effect of extraneous vibrations on the access performance of disk drives has been increasing. Sometimes a cooling fan included in a storage apparatus is one source of such extraneous vibrations. An abnormal vibration is generated in the storage apparatus due to malfunction or faulty assembly of the cooling fan and the access performance of the disk drive is decreased due to the occurrence of abnormalities such as a write off-track error. Such abnormalities are sometimes a hindrance to a data saving function of a redundant array of inexpensive/independent disks (RAID) and there is a demand to detect such faults in cooling fans.
Many storage apparatuses monitor the rotational speed of a cooling fan in order to maintain cooling performance but not to detect extraneous vibrations. However, there are storage apparatuses capable of detecting extraneous vibrations, for example, by using an acceleration sensor mounted therein.
Related techniques are disclosed in, for example, Japanese Laid-open Patent Publication No. 2012-94214, Japanese Laid-open Patent Publication No. 2009-3665, Japanese Laid-open Patent Publication No. 2008-208806, and Japanese Laid-open Patent Publication No. 2004-207450.
Extraneous vibrations in storage apparatuses do not necessarily cause the access performance of the disk drive to be reduced. Consequently, excessive detection of abnormalities leads to a reduction in cooling performance due to disconnection of normal cooling fans and to a reduction in the reliability of abnormality reports due to excessive reporting of abnormalities.